selftests/bpf: add tests for subtraction & negative numbers
Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Edward Cree
David S. Miller
parent
1f9ab38f8a
commit
f999d64c34
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@ -497,6 +497,110 @@ static struct bpf_align_test tests[] = {
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{16, "R6=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
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}
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},
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{
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.descr = "variable subtraction",
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.insns = {
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/* Create an unknown offset, (4n+2)-aligned */
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LOAD_UNKNOWN(BPF_REG_6),
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BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
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BPF_ALU64_IMM(BPF_LSH, BPF_REG_6, 2),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 14),
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/* Create another unknown, (4n)-aligned, and subtract
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* it from the first one
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*/
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BPF_ALU64_IMM(BPF_LSH, BPF_REG_7, 2),
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BPF_ALU64_REG(BPF_SUB, BPF_REG_6, BPF_REG_7),
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/* Bounds-check the result */
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BPF_JMP_IMM(BPF_JSGE, BPF_REG_6, 0, 1),
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BPF_EXIT_INSN(),
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/* Add it to the packet pointer */
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BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
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BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_6),
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/* Check bounds and perform a read */
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BPF_MOV64_REG(BPF_REG_4, BPF_REG_5),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
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BPF_JMP_REG(BPF_JGE, BPF_REG_3, BPF_REG_4, 1),
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BPF_EXIT_INSN(),
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BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_5, 0),
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BPF_EXIT_INSN(),
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},
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.prog_type = BPF_PROG_TYPE_SCHED_CLS,
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.matches = {
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/* Calculated offset in R6 has unknown value, but known
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* alignment of 4.
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*/
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{7, "R2=pkt(id=0,off=0,r=8,imm=0)"},
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{9, "R6=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
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/* Adding 14 makes R6 be (4n+2) */
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{10, "R6=inv(id=0,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
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/* New unknown value in R7 is (4n) */
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{11, "R7=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
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/* Subtracting it from R6 blows our unsigned bounds */
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{12, "R6=inv(id=0,smin_value=-1006,smax_value=1034,var_off=(0x2; 0xfffffffffffffffc))"},
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/* Checked s>= 0 */
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{14, "R6=inv(id=0,umin_value=2,umax_value=1034,var_off=(0x2; 0x7fc))"},
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/* At the time the word size load is performed from R5,
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* its total fixed offset is NET_IP_ALIGN + reg->off (0)
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* which is 2. Then the variable offset is (4n+2), so
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* the total offset is 4-byte aligned and meets the
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* load's requirements.
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*/
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{20, "R5=pkt(id=1,off=0,r=4,umin_value=2,umax_value=1034,var_off=(0x2; 0x7fc))"},
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},
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},
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{
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.descr = "pointer variable subtraction",
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.insns = {
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/* Create an unknown offset, (4n+2)-aligned and bounded
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* to [14,74]
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*/
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LOAD_UNKNOWN(BPF_REG_6),
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BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
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BPF_ALU64_IMM(BPF_AND, BPF_REG_6, 0xf),
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BPF_ALU64_IMM(BPF_LSH, BPF_REG_6, 2),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 14),
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/* Subtract it from the packet pointer */
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BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
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BPF_ALU64_REG(BPF_SUB, BPF_REG_5, BPF_REG_6),
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/* Create another unknown, (4n)-aligned and >= 74.
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* That in fact means >= 76, since 74 % 4 == 2
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*/
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BPF_ALU64_IMM(BPF_LSH, BPF_REG_7, 2),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 76),
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/* Add it to the packet pointer */
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BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_7),
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/* Check bounds and perform a read */
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BPF_MOV64_REG(BPF_REG_4, BPF_REG_5),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
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BPF_JMP_REG(BPF_JGE, BPF_REG_3, BPF_REG_4, 1),
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BPF_EXIT_INSN(),
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BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_5, 0),
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BPF_EXIT_INSN(),
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},
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.prog_type = BPF_PROG_TYPE_SCHED_CLS,
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.matches = {
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/* Calculated offset in R6 has unknown value, but known
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* alignment of 4.
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*/
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{7, "R2=pkt(id=0,off=0,r=8,imm=0)"},
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{10, "R6=inv(id=0,umax_value=60,var_off=(0x0; 0x3c))"},
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/* Adding 14 makes R6 be (4n+2) */
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{11, "R6=inv(id=0,umin_value=14,umax_value=74,var_off=(0x2; 0x7c))"},
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/* Subtracting from packet pointer overflows ubounds */
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{13, "R5=pkt(id=1,off=0,r=8,umin_value=18446744073709551542,umax_value=18446744073709551602,var_off=(0xffffffffffffff82; 0x7c))"},
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/* New unknown value in R7 is (4n), >= 76 */
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{15, "R7=inv(id=0,umin_value=76,umax_value=1096,var_off=(0x0; 0x7fc))"},
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/* Adding it to packet pointer gives nice bounds again */
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{16, "R5=pkt(id=2,off=0,r=0,umin_value=2,umax_value=1082,var_off=(0x2; 0x7fc))"},
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/* At the time the word size load is performed from R5,
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* its total fixed offset is NET_IP_ALIGN + reg->off (0)
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* which is 2. Then the variable offset is (4n+2), so
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* the total offset is 4-byte aligned and meets the
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* load's requirements.
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*/
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{20, "R5=pkt(id=2,off=0,r=4,umin_value=2,umax_value=1082,var_off=(0x2; 0x7fc))"},
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},
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},
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};
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static int probe_filter_length(const struct bpf_insn *fp)
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